The premise that the complex carbohydrates of the cell surface are important in intercellular recognition during differentiation and growth control is widely held. In addition it is widely accepted that changes in the complex carbohydrates of the cell surface occur as part of the alteration of the cell surface during malignant transformation. However, the carbohydrate structures involved in intercellular recognition have not been identified nor have the changes which occur during malignant transformation been characterized in molecular detail. The objective of the research proposed here is to approach these problems using direct structural studies. These studies will focus on the glycoproteins of the cell surface. The glycoproteins chosen for detailed study are those for which there are some preliminary indications of changes during malignant transformation. One such species is a trypsin sensitive glycoprotein from the surface of chick embryo fibroblasts. This glycoprotein will be purified from chick cells. The individual oligosaccharide structures of this glycoprotein will be purified. Their structures will be examined using methylation analysis and sequential enzymatic degradation with specific glycosidases. The envelope glycoproteins of Sindbis virus will lso be studied. By studying the structure of purified glycopeptides from Sindbis virus grown in normal and Rous sarcoma virus transformed chick cells, it is hoped that the changes which occur in the host cell can be defined. Since the carbohydrates of the Sindbis glycoproteins are assembled by host glycosyl transferases, the changes in host carbohydrate metabolism caused by transformation should be reflected in the carbohydrates of Sindbis virus grown in transformed cells. By identifying the changes in carbohydrate structure which occur during malignant transformation and correlating these with alterations in the biological properties of the cell surface it should be possible to gain information about structures that are important in the intercellular recognition responsible for growth control.